烟花飘落恋红尘烟花散去弃红尘
[yān huā piāo luò liàn hóng chén yān huā sàn qù qì hóng chén]
This refers to falling in love passionately during a spectacular moment like firework display in earthly life (love/hate/joy/sorrow) then after the fireworks have faded away leaving everything behind and becoming uninterested in the secular world or emotions again.